<?php

namespace Kirby\Toolkit;

use Kirby\Filesystem\F;
use Kirby\Http\Uri;
use Kirby\Http\Url;

/**
 * HTML builder for the most common elements
 *
 * @package   Kirby Toolkit
 * @author    Bastian Allgeier <bastian@getkirby.com>
 * @link      https://getkirby.com
 * @copyright Bastian Allgeier
 * @license   https://opensource.org/licenses/MIT
 */
class Html extends Xml
{
	/**
	 * An internal store for an HTML entities translation table
	 *
	 * @var array
	 */
	public static $entities;

	/**
	 * List of HTML tags that can be used inline
	 *
	 * @var array
	 */
	public static $inlineList = [
		'b',
		'i',
		'small',
		'abbr',
		'cite',
		'code',
		'dfn',
		'em',
		'kbd',
		'strong',
		'samp',
		'var',
		'a',
		'bdo',
		'br',
		'img',
		'q',
		'span',
		'sub',
		'sup'
	];

	/**
	 * Closing string for void tags;
	 * can be used to switch to trailing slashes if required
	 *
	 * ```php
	 * Html::$void = ' />'
	 * ```
	 *
	 * @var string
	 */
	public static $void = '>';

	/**
	 * List of HTML tags that are considered to be self-closing
	 *
	 * @var array
	 */
	public static $voidList = [
		'area',
		'base',
		'br',
		'col',
		'command',
		'embed',
		'hr',
		'img',
		'input',
		'keygen',
		'link',
		'meta',
		'param',
		'source',
		'track',
		'wbr'
	];

	/**
	 * Generic HTML tag generator
	 * Can be called like `Html::p('A paragraph', ['class' => 'text'])`
	 *
	 * @param string $tag Tag name
	 * @param array $arguments Further arguments for the Html::tag() method
	 * @return string
	 */
	public static function __callStatic(string $tag, array $arguments = []): string
	{
		if (static::isVoid($tag) === true) {
			return static::tag($tag, null, ...$arguments);
		}

		return static::tag($tag, ...$arguments);
	}

	/**
	 * Generates an `<a>` tag; automatically supports mailto: and tel: links
	 *
	 * @param string $href The URL for the `<a>` tag
	 * @param string|array|null $text The optional text; if `null`, the URL will be used as text
	 * @param array $attr Additional attributes for the tag
	 * @return string The generated HTML
	 */
	public static function a(string $href, $text = null, array $attr = []): string
	{
		if (Str::startsWith($href, 'mailto:')) {
			return static::email(substr($href, 7), $text, $attr);
		}

		if (Str::startsWith($href, 'tel:')) {
			return static::tel(substr($href, 4), $text, $attr);
		}

		return static::link($href, $text, $attr);
	}

	/**
	 * Generates a single attribute or a list of attributes
	 *
	 * @param string|array $name String: A single attribute with that name will be generated.
	 *                           Key-value array: A list of attributes will be generated. Don't pass a second argument in that case.
	 * @param mixed $value If used with a `$name` string, pass the value of the attribute here.
	 *                     If used with a `$name` array, this can be set to `false` to disable attribute sorting.
	 * @param string|null $before An optional string that will be prepended if the result is not empty
	 * @param string|null $after An optional string that will be appended if the result is not empty
	 * @return string|null The generated HTML attributes string
	 */
	public static function attr($name, $value = null, ?string $before = null, ?string $after = null): ?string
	{
		// HTML supports boolean attributes without values
		if (is_array($name) === false && is_bool($value) === true) {
			return $value === true ? strtolower($name) : null;
		}

		// all other cases can share the XML variant
		$attr = parent::attr($name, $value);

		if ($attr === null) {
			return null;
		}

		// HTML supports named entities
		$entities = parent::entities();
		$html = array_keys($entities);
		$xml  = array_values($entities);
		$attr = str_replace($xml, $html, $attr);

		if ($attr) {
			return $before . $attr . $after;
		}

		return null;
	}

	/**
	 * Converts lines in a string into HTML breaks
	 *
	 * @param string $string
	 * @return string
	 */
	public static function breaks(string $string): string
	{
		return nl2br($string);
	}

	/**
	 * Generates an `<a>` tag with `mailto:`
	 *
	 * @param string $email The email address
	 * @param string|array|null $text The optional text; if `null`, the email address will be used as text
	 * @param array $attr Additional attributes for the tag
	 * @return string The generated HTML
	 */
	public static function email(string $email, $text = null, array $attr = []): string
	{
		if (empty($email) === true) {
			return '';
		}

		if (empty($text) === true) {
			// show only the email address without additional parameters
			$address = Str::contains($email, '?') ? Str::before($email, '?') : $email;

			$text = [Str::encode($address)];
		}

		$email = Str::encode($email);
		$attr  = array_merge([
			'href' => [
				'value'  => 'mailto:' . $email,
				'escape' => false
			]
		], $attr);

		// add rel=noopener to target blank links to improve security
		$attr['rel'] = static::rel($attr['rel'] ?? null, $attr['target'] ?? null);

		return static::tag('a', $text, $attr);
	}

	/**
	 * Converts a string to an HTML-safe string
	 *
	 * @param string|null $string
	 * @param bool $keepTags If true, existing tags won't be escaped
	 * @return string The HTML string
	 *
	 * @psalm-suppress ParamNameMismatch
	 */
	public static function encode(?string $string, bool $keepTags = false): string
	{
		if ($string === null) {
			return '';
		}

		if ($keepTags === true) {
			$list = static::entities();
			unset($list['"'], $list['<'], $list['>'], $list['&']);

			$search = array_keys($list);
			$values = array_values($list);

			return str_replace($search, $values, $string);
		}

		return htmlentities($string, ENT_QUOTES, 'utf-8');
	}

	/**
	 * Returns the entity translation table
	 *
	 * @return array
	 */
	public static function entities(): array
	{
		return self::$entities ??= get_html_translation_table(HTML_ENTITIES);
	}

	/**
	 * Creates a `<figure>` tag with optional caption
	 *
	 * @param string|array $content Contents of the `<figure>` tag
	 * @param string|array $caption Optional `<figcaption>` text to use
	 * @param array $attr Additional attributes for the `<figure>` tag
	 * @return string The generated HTML
	 */
	public static function figure($content, $caption = '', array $attr = []): string
	{
		if ($caption) {
			$figcaption = static::tag('figcaption', $caption);

			if (is_string($content) === true) {
				$content = [static::encode($content, false)];
			}

			$content[] = $figcaption;
		}

		return static::tag('figure', $content, $attr);
	}

	/**
	 * Embeds a GitHub Gist
	 *
	 * @param string $url Gist URL
	 * @param string|null $file Optional specific file to embed
	 * @param array $attr Additional attributes for the `<script>` tag
	 * @return string The generated HTML
	 */
	public static function gist(string $url, ?string $file = null, array $attr = []): string
	{
		if ($file === null) {
			$src = $url . '.js';
		} else {
			$src = $url . '.js?file=' . $file;
		}

		return static::tag('script', '', array_merge($attr, ['src' => $src]));
	}

	/**
	 * Creates an `<iframe>`
	 *
	 * @param string $src
	 * @param array $attr Additional attributes for the `<iframe>` tag
	 * @return string The generated HTML
	 */
	public static function iframe(string $src, array $attr = []): string
	{
		return static::tag('iframe', '', array_merge(['src' => $src], $attr));
	}

	/**
	 * Generates an `<img>` tag
	 *
	 * @param string $src The URL of the image
	 * @param array $attr Additional attributes for the `<img>` tag
	 * @return string The generated HTML
	 */
	public static function img(string $src, array $attr = []): string
	{
		$attr = array_merge([
			'src' => $src,
			'alt' => ' '
		], $attr);

		return static::tag('img', '', $attr);
	}

	/**
	 * Checks if a tag is self-closing
	 *
	 * @param string $tag
	 * @return bool
	 */
	public static function isVoid(string $tag): bool
	{
		return in_array(strtolower($tag), static::$voidList);
	}

	/**
	 * Generates an `<a>` link tag (without automatic email: and tel: detection)
	 *
	 * @param string $href The URL for the `<a>` tag
	 * @param string|array|null $text The optional text; if `null`, the URL will be used as text
	 * @param array $attr Additional attributes for the tag
	 * @return string The generated HTML
	 */
	public static function link(string $href, $text = null, array $attr = []): string
	{
		$attr = array_merge(['href' => $href], $attr);

		if (empty($text) === true) {
			$text = $attr['href'];
		}

		if (is_string($text) === true && V::url($text) === true) {
			$text = Url::short($text);
		}

		// add rel=noopener to target blank links to improve security
		$attr['rel'] = static::rel($attr['rel'] ?? null, $attr['target'] ?? null);

		return static::tag('a', $text, $attr);
	}

	/**
	 * Add noopener & noreferrer to rels when target is `_blank`
	 *
	 * @param string|null $rel Current `rel` value
	 * @param string|null $target Current `target` value
	 * @return string|null New `rel` value or `null` if not needed
	 */
	public static function rel(?string $rel = null, ?string $target = null): ?string
	{
		$rel = trim($rel ?? '');

		if ($target === '_blank') {
			if (empty($rel) === false) {
				return $rel;
			}

			return trim($rel . ' noopener noreferrer', ' ');
		}

		return $rel;
	}

	/**
	 * Builds an HTML tag
	 *
	 * @param string $name Tag name
	 * @param array|string $content Scalar value or array with multiple lines of content; self-closing
	 *                              tags are generated automatically based on the `Html::isVoid()` list
	 * @param array $attr An associative array with additional attributes for the tag
	 * @param string|null $indent Indentation string, defaults to two spaces or `null` for output on one line
	 * @param int $level Indentation level
	 * @return string The generated HTML
	 */
	public static function tag(string $name, $content = '', array $attr = null, string $indent = null, int $level = 0): string
	{
		// treat an explicit `null` value as an empty tag
		// as void tags are already covered below
		if ($content === null) {
			$content = '';
		}

		// force void elements to be self-closing
		if (static::isVoid($name) === true) {
			$content = null;
		}

		return parent::tag($name, $content, $attr, $indent, $level);
	}

	/**
	 * Generates an `<a>` tag for a phone number
	 *
	 * @param string $tel The phone number
	 * @param string|array|null $text The optional text; if `null`, the phone number will be used as text
	 * @param array $attr Additional attributes for the tag
	 * @return string The generated HTML
	 */
	public static function tel(string $tel, $text = null, array $attr = []): string
	{
		$number = preg_replace('![^0-9\+]+!', '', $tel);

		if (empty($text) === true) {
			$text = $tel;
		}

		return static::link('tel:' . $number, $text, $attr);
	}

	/**
	 * Properly encodes tag contents
	 *
	 * @param mixed $value
	 * @return string|null
	 */
	public static function value($value): ?string
	{
		if ($value === true) {
			return 'true';
		}

		if ($value === false) {
			return 'false';
		}

		if (is_numeric($value) === true) {
			return (string)$value;
		}

		if ($value === null || $value === '') {
			return null;
		}

		return static::encode($value, false);
	}

	/**
	 * Creates a video embed via `<iframe>` for YouTube or Vimeo
	 * videos; the embed URLs are automatically detected from
	 * the given URL
	 *
	 * @param string $url Video URL
	 * @param array $options Additional `vimeo` and `youtube` options
	 *                       (will be used as query params in the embed URL)
	 * @param array $attr Additional attributes for the `<iframe>` tag
	 * @return string|null The generated HTML
	 */
	public static function video(string $url, array $options = [], array $attr = []): ?string
	{
		// YouTube video
		if (Str::contains($url, 'youtu', true) === true) {
			return static::youtube($url, $options['youtube'] ?? [], $attr);
		}

		// Vimeo video
		if (Str::contains($url, 'vimeo', true) === true) {
			return static::vimeo($url, $options['vimeo'] ?? [], $attr);
		}

		// self-hosted video file
		$extension = F::extension($url);
		$type      = F::extensionToType($extension);
		$mime      = F::extensionToMime($extension);

		// ignore unknown file types
		if ($type !== 'video') {
			return null;
		}

		return static::tag('video', [
			static::tag('source', null, [
				'src'  => $url,
				'type' => $mime
			])
		], $attr);
	}

	/**
	 * Generates a list of attributes
	 * for video iframes
	 *
	 * @param array $attr
	 * @return array
	 */
	public static function videoAttr(array $attr = []): array
	{
		// allow fullscreen mode by default
		// and use new `allow` attribute
		if (
			isset($attr['allow']) === false &&
			($attr['allowfullscreen'] ?? true) === true
		) {
			$attr['allow'] = 'fullscreen';
			$attr['allowfullscreen'] = true;
		}

		return $attr;
	}

	/**
	 * Embeds a Vimeo video by URL in an `<iframe>`
	 *
	 * @param string $url Vimeo video URL
	 * @param array $options Query params for the embed URL
	 * @param array $attr Additional attributes for the `<iframe>` tag
	 * @return string|null The generated HTML
	 */
	public static function vimeo(string $url, array $options = [], array $attr = []): ?string
	{
		$uri   = new Uri($url);
		$path  = $uri->path();
		$query = $uri->query();
		$id    = null;

		switch ($uri->host()) {
			case 'vimeo.com':
			case 'www.vimeo.com':
				$id = $path->last();
				break;
			case 'player.vimeo.com':
				$id = $path->nth(1);
				break;
		}

		if (empty($id) === true || preg_match('!^[0-9]*$!', $id) !== 1) {
			return null;
		}

		// append query params
		foreach ($options as $key => $value) {
			$query->$key = $value;
		}

		// build the full video src URL
		$src = 'https://player.vimeo.com/video/' . $id . $query->toString(true);

		return static::iframe($src, static::videoAttr($attr));
	}

	/**
	 * Embeds a YouTube video by URL in an `<iframe>`
	 *
	 * @param string $url YouTube video URL
	 * @param array $options Query params for the embed URL
	 * @param array $attr Additional attributes for the `<iframe>` tag
	 * @return string|null The generated HTML
	 */
	public static function youtube(string $url, array $options = [], array $attr = []): ?string
	{
		if (preg_match('!youtu!i', $url) !== 1) {
			return null;
		}

		$uri    = new Uri($url);
		$path   = $uri->path();
		$query  = $uri->query();
		$first  = $path->first();
		$second = $path->nth(1);
		$host   = 'https://' . $uri->host() . '/embed';
		$src    = null;

		$isYoutubeId = function (?string $id = null): bool {
			if (empty($id) === true) {
				return false;
			}

			return preg_match('!^[a-zA-Z0-9_-]+$!', $id);
		};

		switch ($path->toString()) {
			case 'embed/videoseries':
			case 'playlist':
				// playlists
				if ($isYoutubeId($query->list) === true) {
					$src = $host . '/videoseries';
				}

				break;

			case 'watch':
				// regular video URLs
				if ($isYoutubeId($query->v) === true) {
					$src = $host . '/' . $query->v;

					$query->start = $query->t;
					unset($query->v, $query->t);
				}

				break;

			default:
				// short URLs
				if (Str::contains($uri->host(), 'youtu.be') === true && $isYoutubeId($first) === true) {
					$src = 'https://www.youtube.com/embed/' . $first;

					$query->start = $query->t;
					unset($query->t);

				// embedded video URLs
				} elseif ($first === 'embed' && $isYoutubeId($second) === true) {
					$src = $host . '/' . $second;
				}
		}

		if (empty($src) === true) {
			return null;
		}

		// append all query parameters
		foreach ($options as $key => $value) {
			$query->$key = $value;
		}

		// build the full video src URL
		$src = $src . $query->toString(true);

		// render the iframe
		return static::iframe($src, static::videoAttr($attr));
	}
}
